Too easy..eh?

C1, C2 and C3 are three tangent circles with their centers on the same line. If R is the radius of the large circle and the diameter of circle C1 is twice the diameter of circle C3, then what is the area of the shaded region?

C1, C2 and C3 are three tangent circles with their centers on the same line. If R is the radius of the large circle and the diameter of circle C1 is twice the diameter of circle C3, then what is the area of the shaded region?